private void DrawArc(float aStartValue, float aEndValue, bool aClockwise)
{
// The angles for this path:
// 0 => along +ve x-axis
// 90 => along +ve y-axis
// i.e. +ve angles go anti-clockwise
NSBezierPath path = new NSBezierPath();
path.LineWidth = iLineWidth;
float startAngle = iZeroAngle - (360.0f * aStartValue / iMaxValue);
float endAngle = iZeroAngle - (360.0f * aEndValue / iMaxValue);
path.AppendBezierPathWithArcWithCenterRadiusStartAngleEndAngleClockwise(
new NSPoint(Bounds.Width * 0.5f, Bounds.Height * 0.5f),
iRadius, startAngle, endAngle, aClockwise);
path.Stroke();
path.Release();
}